The present invention relates to a fixture and method for keying a keyless shaft and specifically, to keying a keyless engine crankshaft.
Most automotive engines utilize a harmonic damper installed on the end of the crankshaft to counteract torsion and vibration inherent in the rotating crankshaft. In the past, the crankshaft was usually provided with a key so that the harmonic damper having a keyway could be keyed to the crankshaft to prevent rotation of the harmonic damper with respect to the crankshaft. A bolt threaded into the end of the crankshaft then locked the harmonic damper to the crankshaft. Currently, certain engines, including specifically, the high performance LS1® engine from Chevrolet®, are not provided with keyed crankshafts or harmonic dampers. Rather, the harmonic damper is not keyed to the crankshaft but is merely bolted onto the end of the crankshaft with no specific angular orientation with respect to the crankshaft. However, under certain high performance operating conditions, it has been found that the harmonic damper can spin on the crankshaft with undesirable consequences. This has been found to be especially the case for LS1® engines that are supercharged, with the supercharging blower being belt driven by a pulley mounted to the harmonic damper. The increased forces imposed on the harmonic damper from driving the blower can overcome the unkeyed connection and cause the harmonic damper to rotate on the crankshaft. Such rotation results in decreased power output, rapidly destruction of the crankshaft and harmonic damper and can even cause catastrophic engine failure because of crankshaft breakage.
In the past, the only effective way to key a keyless crankshaft, or add a key to a keyed crankshaft, was to remove the crankshaft from the engine for machining. This is time consuming, expensive and opens the interior of the engine to risk of contamination.